<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>打印金字塔</title>
	</head>
	<body>
		<script type="text/javascript">
        var a=prompt("输入每层星星数：");
        document.write("<p align='center'>");
        for (var i=1;i<=a;i++){
        	for(j=1;j<=2*i-1;j++){
            document.write("*");
        	}
        	document.write("<br/>")
        }
        </script>
	</body>
</html>
